The Kidde Battery Powered Carbon Monoxide & Smoke Alarm with Voice Commands offers the utility of two safety devices. Its been proven that children respond better to a real voice that any standard alarm, so it combines a unique voice warning with details to let everyone in the home know if they are facing the dangers of fire or carbon monoxide in simplistically formed commands. The system also tells owners when a battery is low and has a smart hush feature. The unit works on (3) Standard AA batteries and is not dependant on electricity in your home working during the time of an emergency. The unit also features a duo of LED indicators, an easy to use test button, a low battery indicator, and the smart hush to silence false alarms. No wiring required for installation. 5.75 diameter. Ceiling or wall mounted.